In recent years, digital cameras that are used to input imaging information of landscapes, persons, etc., into a personal computer have been rapidly increasing in popularity as the use of the personal computer in our daily life increases. The digital camera is an instrument which converts optical images into electrical signals using an image sensor such as a charge coupled device (CCD) and records them as digital image data. Conventional imaging lenses for use in digital cameras are disclosed in Japanese Laid Open Patent Applications H5-157962 and H11-125767.
Generally speaking, digital cameras are required to have a compact construction and to provide high-resolution images. Thus, the lens used in digital cameras must be compact and provide a high resolution. In addition, due to the requirements of CCD image sensors, it is desirable that the light rays that are incident onto the image sensor surface be nearly perpendicular to the detecting surface. Therefore, it is desirable that the imaging lens used in a digital camera be nearly telecentric. The imaging lenses disclosed in Japanese Laid Open Patent Applications H5-157962 and H11-125767 do not satisfy the requirements of compactness, high resolution, and low production cost as is needed for digital cameras that require a high resolution.
The present invention relates to a single focus lens, more particularly, one suitable for use in a digital still camera (hereinafter referred to simply as a digital camera). The object of the present invention is to provide a single focus lens having a high resolution and low production cost that is suitable for use in a digital camera having a compact construction.